Recently, there is an increasing interest in water quality of a water supply. Accordingly, a water pipe formed of stainless steel that is known as the most suitable pipe for the water quality is under the spotlight.
The water pipe embedded under the ground to supply running water has to have corrosion resistance for protecting the water quality therein. Also, watertightness in a connection part, separation prevention ability due to a water pressure, convenience in installation, and structural stability for the changes of external environments are required. A stainless steel pipe is known as a pipe having material characteristics that are most suitable for conditions required for this water pipe. If the stainless steel pipe has a relatively small diameter of about 13 A (0.8 T) to about 50 A (1.2 T), a press-type pipe fitting in which a rubber ring is inserted into a socket of which a pipe end is expanded, and a pipe is pushed to bond the pipes in a press type manner using a mechanical force may be used.
However, since the stainless steel pipe having a diameter of about 80 A or more has a thickness of about 2.0 T or more, it is impossible to perform works in a site in the press type manner. Thus, a welding operation has to be performed to connect the pipes. Here, it is significantly difficult to weld and connect the pipes each of which has a diameter of about 80 A or more in the work site, and thus a skilled engineer for welding may be needed, and a working process may be delayed.
Therefore, the water pipe having a diameter of about 80 A or more mostly adopts a cast iron pipe. However, since the cast iron pipe is heavy, it is difficult to be transported and installed, and when a branch pipe is provided, rust can occur around a fumarole. Also, a separate coating process has to be performed to prevent the rust from occurring on the pipe, thereby incurring excessive manufacturing costs.
To solve the limitations in the related art, there is Korean Patent Registration No. 10-0999881, which is entitled as “stainless steel pipe for water supply (hereinafter, referred to as a “related art”)”. The related art is characterized in that a synthetic resin coating layer is formed on an outer surface of the stainless steel pipe.
However, since the synthetic resin coating layer is formed on the outer surface of the stainless steel pipe, manufacturing costs are expensive. Also, when stainless pipes are connected to each other, a pre-task in which a fixing band is coupled to an outer diameter portion of a pipe insertion part of one side of the stainless pipe is needed, and then an exclusive work tool has to be used to connect the stainless pipes to each other, and thus the work is not simple. Here, improvement in connection of the stainless steel pipe are required.
Also, since the stainless steel pipe has high rigidity, it is relatively difficult to fix a clamp for connecting the fittings and to make a passive pipe work in the site difficult.
The present invention has been invented to solve the limitations in the related art.